From food to plastic – a biological bonanza

Date:25/09/03

By Karen Carstens

SOMEDAY soon your leftover lunch could be converted into useful items such as trash bags, nappies or even a lunchbox, thanks to a biological reactor developed by scientists in Hawaii that transforms a slurry of food waste into biodegradable plastic.

The polymer created could also be used to make greener packaging or pills that dissolve slowly to release drugs in the body.

"It's a simple, economical, energy-saving way to convert food wastes into bioplastics," said Jian Yu, a biochemical engineer at the Honolulu-based Hawaii Natural Energy Institute.

"My research began in 1995, while I was at the Hong Kong University of Science and Technology," Yu told Honolulu Magazine earlier this year. "Hong Kong faces a similar problem to Honolulu's, with a growing population, growing amounts of waste and limited space."

More than 22 million tonnes of waste food are discarded each year in the US alone. It makes landfills stink and releases the greenhouse gas methane, and the reeking contents can also find their way into the groundwater.

Yu and his colleagues at the institute, affiliated with the University of Hawaii, figured out a way to put these food scraps to good use, and cut the cost of making biodegradable plastic in the process.

"People discard organic waste materials during food production and consumption. We collect and turn organic waste into slurry, and use natural microbes to break it into simple fermentative compounds such as acetic, propionic and butric acids," he explained.

"From these fermentative acids, some special microbial strains, isolated from soil, produce bioplastics under a controlled environment. The waste residuals that cannot be decomposed by the natural microbes are further stabilized as excellent soil conditioner and organic fertilizer."

The idea is not new. The British chemicals company ICI started making a biodegradable polymer (PHB) about ten years ago. Although popular, PHB was ten times as expensive as standard polymers because it was made using pure sugar and an organic acid.

Yet Yu says he has now found a cheaper way to make PHB, claiming his technique significantly reduces the cost of producing bioplastics from about &036;4.50 (€4) to between &036;1 and &036;2 (around 88 euro cents to €1.76) per pound (454 grammes).

Yu has signed a licence agreement with I-PHA BioPolymers of Hong Kong to use the technology he developed to produce bioplastics and organic fertilizers in Hong Kong, Macau and China, according to the University of Hawaii.

"I am grateful for I-PHA BioPolymers willingness to make an investment in a technology that can truly make a difference in our lives," Richard Cox, director of the university's technology transfer and economic development office, said.

"By helping commercialize this technology, I-PHA BioPolymers will be helping to tackle one of those thorny problems that confront virtually every country on earth - solid waste management and overflowing landfills - and that will be a benefit to us all, truly a benefit to society."

In Hong Kong, I-PHA BioPolymers will commission a research centre to develop and build a pilot plant to produce bioplastics and organic fertilizers using the new technology. Yu will be chief scientist for the pilot plant design and construction.

Andy Lo, the company's managing director, praised Yu's food slurry technique as "a cost-effective approach to handling biodegradable organic waste materials by converting it into bioplastics and organic fertilizers without secondary pollution."

A biological reactor development by scientists in Hawaii can convert food wastes into bioplastics, saving money, energy and the environment.